If the lands of any such entryman shall at any time revert to the United States for any reason whatever, all such liens or tax titles resulting from assessments levied after June 13, 1930, upon such lands in favor of the State or political subdivision thereof wherein the lands are located, shall be and shall be held to have been, thereupon extinguished; and the levying of any such assessment by such State or political subdivision shall be deemed to be an agreement on its part, in the event of such reversion, to execute and record a formal release of such lien or tax title.